Process of distilling coal



Feb. 18 1936.

G. A. BERRY ET AL PROJESS 0F DISTILLING COAL Original Fil'ed Nov. 16,1.923 2 Sheets-Sheet 1 32% yv zm'ons 2g. BY; I ,5 g l ATTORNEYS Feb.18,1936. G. A. BERRY ET AL PROCESS OF DISTILLING COAL 2 sheets-sheet 2Original Filed Nov. 16, 1923 ATTORN EYJ Patented Feb. 18, 1936 UNITEDSTATES PATENT orrlcr. I

Beardsley, Plainfield,

N. .L, assignors to National Fuels Corporation, New York, N. Y., a.corporation of New Jersey Application November 16, 1928, Serial No.319,798 Renewed May 14, 1935 16 Claims.

The primary object of this invention is broadly the transformation ofbituminous coal into a carbonized fuel, closely resembling anthracite,and into other valuable products. Another object is to accomplish theabove at such a low cost as to be commercially profitable.

By this invention we are also able to recover very valuable commoditiesfrom the so-called slack which is produced in enormous quantities in themining and transportation of bituminous coal and which has beenconsidered as of so little value as to command only a small fraction ofthe price of the bituminous coal itself.

By this invention the coal is transformed into the followingcommodities:

A. An acceptabie substitute for natural anthracite which will in somerespects be the superior and in others the equal of the natural product,being (1) in pieces of desirable size, (2) of sufiioient strength forhandling, (3) of (4) of not too rapid or active combustion, (5) ofsufiicient ignitability, (6) of smokeless combustion, (7) sufiicientlyfree from dust or fines, (8) of low ash content when made from suitablebituminous coals, many of which are of much less ash content than theaverage anthracite and (9) of high calorific value per volume unit.

B. A high yield of organic liquids condensible at ordinary temperatureand in primary condition or, in other words, in substantially the samecondition in which they were first evolved from the coal and hencepractically unchanged by cracking or otherwise.

C. Gases and vapors not condensible at ordinary temperatures and ofcalorific value considerably higher than ordinary coal gas.

D. Gases of less calorific value not condensible at ordinarytemperatures.

These commodities are productible from a wide variety of grades orcharacters of bituminous coal, of which for example the coal fields ofeastern United States afford a practically unlimited supply.

From the description given later on in connection with the drawings itwill be found that this treatment is accomplished in stages, each ofwhich involves its current of heatingv gas, namely:

1. The first stage involves the heating of the coal by passing a currentof hot gas, such as coal gas of a temperature between about 275 C. and400 C. therethrough until the temperature of the coal reaches apredetermined point, above 55 which appreciable amounts of tar vapors orproper density in the lump (i. e. 1.2 or higher),

hydrocarbon products condensible at ordinary I temperatures wouldappear. The maximum temperature reached in this stage will depend uponthe nature of the material which is being treated, but we have foundthat with coal of the Pocahontas or New River type the temperature ofthe coal in this stage will ordinarily reach somewhere between 275 and400 C-. The increment of temperature of the coal per unit of time duringthis stage can be quite rapid (e. g. at the rate of 5 C. rise perminute) without injurious efiects. 2. In the second stage substantiallyall the tar vapors as well as the hydrocarbons condensible at ordinarytemperature are removed from the coal by the current of gas which may becoal gas and a small amount of permanent gas of very high calorificpower is removed at the same time. During this stage the coal becomesplastic and the temperature of the gas passing through the coal isgradually raised from that at the end of the first stage until thetemperature of the coal reaches about 500 C. During the whole or a partof this stage the coal would swell to an extent incompatible with thedesired density of the final product if the rise of temperature were asrapid as it may be in other stages. To obviate this danger the rate ofincrease of temperature of the. coal does not exceed the rate whichtests have shown to be permissible for the particular coal, which ratemay be, for example, with Pocahontas or New River coal, less than aboutone-fourth of a degree C. per minute, during the period when this dangerexists. In general the larger the briquette or lump the slower will bethe rate of temperature increment. 3. In the third stage a current ofgas such as coal gas of still higher temperature beginning at thetemperature of that at the end of the second stage is passed through thecoal, during which time permanent gas of less high calorific power thanthat evolved during the second stage, is obtained. The rate of increaseof the temperature of the coal during the third stage may be quite rapid(e. g. 5 C. per minute) without danger of causing the coal to swell. Thesolid product usually shrinks more and more as the temperature risesduring this stage, thus acquiring increased density and hardness. Thefinal temperature of the carbonized residue may be from about 600 to 900C. according to the re-. activity and density desired in the finalproduct.

4. A fourth or cooling stage may be used in which a current of cool gas,such as coal gas, is passed through the retorts for cooling the residuebefore it is discharged from the retorts into the atmosphere, thuspreventing the same from igniting, and recovering the heat therefrom.The temperature of this gas should be low enough to reduce thetemperature in the retorts below the ignition temperature of the residuein a reasonable time.

For practical purposes we regulate the temperature of the coal in allstages by the temperature and rate of flow of the gas entering theretort.

The process by which said transformation is accomplished is of low cost.It avoids deposition of tar on coal of decidedly lower temperature thanthe temperature of evolution of the tar, and the subsequent distillationof this tar and the consequent degradation of its value. The very richand valuable gas evolved in stage 2 may be withdrawn from the system forsubsequent disposal, as for example, for enriching city gas.

This process comprehends the treatment of not only bituminous coal ofone type but blends of several types thereof and also blends ofbituntnous coal with anthracite, semi-anthracite, su bituminous,lignite, semi-coke and coke, all of which types and blends, as well asbriquettes made from same whether with or without binder, we include inthe expression coal to be treated. Such blends will often permit a morerapid rate of temperature increment during the second stage ofcarbonization and often give a more dense fuel.

In the accompanying drawings, Figs. 1 and 2 represent diagrammaticallytwo examples of arrangements of apparatus which may be employed in theabove transformation. Although batchwise systems are shown we are not tobe understood as limited thereto.

In Fig. 1, reference character I indicates a series of verticallydisposed retorts that may be provided with openings at the top forintroducing the material to be treated and openings at the bottom forwithdrawing the treated material. A conduit 2 for gases leads to theupper ends of the retorts I and a conduit 3 leads away from the lowerends of the retorts. The conduit 3 is provided with two branches one ofwhich leads through valve 4 to stack 5 and the other through valve 6.Beyond valve 6, the conduit 3 is divided into two branches,

one of which is provided with valves 1 and'8 nearits opposite ends andthe other of which is provided with valves 9 and I0 near its oppositeends.

A heat accumulator II is located: between the branches and may be of anyof the well-known types in which heat is stored by hot gases during oneperiod of time and is given up for heating gases during another period.A valve I2 is provided in the conduit 3 beyond the heat exchanger II andanother branch I3 leads from the conduit 3 through a boiler so that allor a portion of the hot gases can be passed through the boiler I4 forgenerating steam and cooling the gases.

A blower or compressor I5 is provided beyond the boiler for circulatingthe gases through the retorts I. A branch I6 leads all from the conduit3 between the boiler and the blower. Branch It leads through a coolerI'I that may be cooled by cold water, for example, and then to a gasholder I8. From gas holder I8, a pipe I9 provided with valve 20 conductsthe gas away for purposes outside the circuit.

A branch 2| leads from conduit 3 from a point between the boiler I4 andblower I5 to blower 22 and then to heat exchanger 23, which may be ofmultitubular type. pipe 23' leads to cooler or extractor 23A forcondensing or extracting the condensible products from the gas, thenon-condensible vapors and From heat exchanger 23 agas passing throughpipe 23" to heat exchanger '23 but to the opposite side of the tubesfrom that of their first passage through heat exchanger 23.

From heat exchanger 23, a pipe 24 leads to and joins pipe 25 coming fromblower I5. Pipe 24 is provided with avalve 26 close to its junction withpipe 25. A valved branch of pipe 24 leads to a superheater 21 that maybe heated by combustion of gases extracted from the products beingtreated or may be heated in any other convenient way, as by a supply ofcombustible gas delivered through pipe 28 and valve 29. For simplicityonly one superheater with its connections has been shown in thedrawings, but it is to be understood that at least two are provided, sothat one may be heated while the other is supplying heat to thecirculating gas.

Pipe 24 is provided with a branch leading to valve 30 through which gasmay be passed through superheater 21 and out through valve 3| and pipe32 which joins pipe 25. Pipe 24 is also provided with a branch leadingsuccessively through valves 33 and 34 by which gas can be admitted tosuperheater 2'! to be burned by air entering through pipe 35 and valve36, the products of combustion passing out through pipev 31 and valve 38to exhaust flue 39.

Pipe 25 is provided with a valve 40 before its junction with pipe 32.After junction with pipe 32, pipe 25 leads to gas mixing chamber 4|, the

outlet of which extends through a connection having a valve 42 into theconduit 2.

Still referring to Fig. 1, the operation will be described in connectionwith the treatment of bituminous coal of the Pocahontas or New River 1;:

type, but it is to be understood that the invention is not restricted tothis particular coal or to the exact procedure outlined below. The gasemployed is to be practically non-oxidizing on the coal and preferablynon-reactive in other respects. The word gas is used herein in the broadsense including vapor. The word nonoxidizing is used herein assignifying the substantial non-transfer of oxygen from the gas to thecoal under existing conditions. A suitable gas is that evolved from thecoal itself by carbonization. I

The coal may be prepared in briquets of the desired size (e. g. 2 oz.)either by subjecting the coal particles to high pressure alone or by theuse ofpressure with a binder. Or lumps of raw coal of the desired sizemay be used.

The operation is as follows:

It will be assumes that the heat exchanger II is at a temperature ofabout 700 C. from a preceding run; that the water in the-boiler I4 is atabout 200 C. corresponding to the desired steam pressure; that thesuperheater 21 is heated to a ill temperature of about 900 C.; and thatgas is in gas holder I8. The valves 40, 42 and 4 are opened long enoughto permit gas from gas holder I8 to pass through the coal in retorts Iand sweep out the air. When the air has been removed the valve 4 isclosed, the valve 6 opened are open so that very little, if any, of thegas will pass through the boiler I4 or the superheater 21.

heater 21, while at the same time the gas holder I8 maintains thepressure at the inlet of the blower I5 constant. The blower 22 is notoperated during this stage so that none of the gas passes into the heatexchanger 23 and condenser 23A. The heat accumulator II is becomingcooled during this stage. The coal is heated up rapidly at first andthen more slowly. Should the heat supplied by the accumulator not besufficient to heat the material in retorts I to the desired temperature,a portion of the gas is passed through superheater 2'I by opening valves26, 30 and 3| and partly closing valve 40. As soon as the temperature ofthe gas leaving the retorts I is nearly the same as that entering theretorts I, the first stage of the treatment is completed.

For the second stage, the valves 9 and 8 are closed and the valves I andI opened so that all the blower I or the blower 22 can be regulatedduring this stage by regulating the damper I2 to cause some of the gasto pass through the boiler I4 and become cooled, and the temperature ofthe gas in the conduit 2 can be regulated by regulating the damper 40 tocontrol the fraction of the gas that passes through the super- Thetemperature of the gas in conduit 2 should be gradually increased duringthis stage and this stage is completed when substantially all of thecondensible products have been removed from the coal, which will usuallybe the i case when the temperature has reached about 500 C. At thebeginning of this stage of the treatment or as soon as a test sampledrawn at the outlet of the retorts I shows the presence of appreciableamounts of tar or condensible products in the gas, the blower 22 isstarted and run at a speed which will cause part of the gas to pass toheat exchanger 23 and through pipe 23' into the condensing equipment23A. The non-condensible gas which escapes from condenser 23A passesthrough pipe 23" into heat exchanger 23 and enters pipe 24. The speed ofblower 22 is so regulated that the amount of non-condensible gaspassingfrom heat exchanger 23 to pipe 24 is equal to or greater than theamount which it is desired to cause to pass through superheater 21. Bythis means only such gas is passed through superheater 21 as has beenfreed from condensible vapors by cool- 1 ing in 23 and 23A. During thisstage any excess of gas in the circuit caused by the evolution of gasfrom the coal or by the increase of temperature accumulates in holderI8, whence it isrwithdrawn as desired through pipe I 9 and valve 20.However, a portion, or all of this excess gas may be consumed duringthis stage by burning the same in the superheater 21 and not pass intogas holder I8.

During the third stage, blower 22 is stopped, damper 26 is opened anddamper 40 is partially or entirely closed, thus causing a portion or allof the gas to pass through the superheater 21 to increase itstemperature. This heated gas passes from the superheater 21, through thepipe 32 and chamber 4I into conduit 2 where its temperature will beabout 800 C. During this stage the coal will be highly heated and thegas that is evolved at the high temperature will, together ,with thecirculating gas, raise the temperature of the heat accumulator IIpreparatory to the treatment of a second charge of coal. During thisstage any excess of gas in the circuit caused by the evolution of gasfrom the coal or the infrom igniting when removed from the retorts I, itis cooled after the third stage of treatment.

For this purpose dampers I, 8 and I2 are closed while 9 and I0 areopened, thus causing the circulating gas to pass through the coal toab-' stract heat and to become cooled while passing through the boilerI4. When the temperature of the coal has been reduced sufiiciently, theblower I5 is stopped and the valves 42 and 0 are closed, whereupon thecarbonized residue is discharged from the retorts I and a fresh chargeof coal to be treated is, introduced into these retorts to be treated.

The example of apparatus of which Fig. 2 is a diagram differs from thatshown in Fig. 1 as follows:

A series of vertically disposed retorts I' is provided duplicatingretorts I. Conduits 2' .and 3' are provided duplicating conduits 2 and3. The conduit from mixing chamber 4 I is branched, one branchcontrolled by valve 42 leading to retorts I and the other branchcontrolled by valve 42' leading to retorts I'. Conduit 3 is providedwith valve 43 and conduit 3 with valve 43'. Beyond valves 43 and 43'conduits 3 and 3 join and the comb'ned conduit is designated as 3.

Heat accumulator II of Fig. l and the valves controlling it are omittedin Fig. 2, conduit 3" leading directly to boiler I 4.

The apparatus shown in Fig. 2 may be operated as follows:-

It will be assumed that retort-s1 are filled with completely carbonizedresidue from a previous operation at the temperature at which saidoperation has been completed, which will be about 800 C.; that retortsI' are filled with fresh coal to be treated; that gas is in the gasholder I8. The valves 40, 42', 43' and 4 are opened long enough topermit gas from gas holder I8 to pass through the coal in retorts I' andsweep out the air. When the air has been removed the valve 4 is closed,valves 42, 43 and 6 are opened, and the blower I5 is started, thuscausing the gas to begin to circulate through the coal or carbonizedresidue in retorts I and retorts I Valve I2 is open so that very little,if any, of the gas will pass through the boiler I4. The temperature ofthe gas entering retorts I should be about 300 C. and this result isobtained by regulating valves 42 and 42, by which the division of thegas to retorts I and retorts I respectively is controlled. Such afraction of the gas is causedto pass through retorts I that thetemperature of the as in conduit 2 is that desired, namely about 300 C.During this stage the gas holder maintains thgegpressure at the inlet ofthe blower I5 constant. The blower 22 is not operated during thisstageso that none of the gas passes into the heat exchanger 23' and thecondenser 23A. The coal is heated up rapidly at first and then moreslowly. Should the heat supplied by the coal or carbonized residue inretort I not be sufficient to heat the coal in retort I' to the desiredtemperature, a portion of the gas from opening valves 26, 30 and 3|, thesuperheater having previously been heated up to the desired temperaturewhich may be about 800 0. As soon as the temperature of the gas leavingthe retorts l is nearly the same as that entering the retorts, the firststage of the treatment is completed. Then valves 42 and 43 are closed,the coo-led material in retorts l is discharged and the retorts l filledwith fresh material to be treated.

For the second stage, the valve 40 is partially closed and the valves26, 30 and 3| are opened, thus causing a fraction of the gas to passthrough the superheater 21. The temperature of the gas reaching theblower I5 or the blower 22 can be regulated during this stage byregulating the damper 12 to cause some of the gas to pass through theboiler l4 and become cooled, so that the temperature of the gas reachingblower I5 or blower 22 is not high enough to damage those blowers. Thetemperature of the gas in the conduit 2' can be regulated by regulatingthe damper 40 to control'the fraction of the gas that passes through thesuperheater 21. The temperature of the gas in conduit 2 should begradually increased during this stage and this stage is completed whensubstantially all of the condensible products have been removed from thecoal, which will usually be the case when the temperature has reached500 C. At the beginning of this stage of the treatment or as soon as atest sample drawn at the outlet of retorts I shows the presence ofappreciable amounts of tar or condensible products in the gas, theblower 22 is started and run at a speed which will cause part of the gasto pass heat exchanger 23 and condensing equipment 23A. Thenon-condensible gas which escapes from condenser 23A passes through pipe23" and thence through heat exchanger 23 and enters pipe 24. Thespeed ofthe blower 22 is so regulated that the amount of non-condensible gaspassing from heat exchanger 23 to pipe 24 is equal to or greater thanthe amount which it is desired to cause to pass through superheater 21.By this means only such gas is passed through superheater 21 as has beenfreed from condensible vapors by cooling in 23 and 23A. During thisstage any excess of gas in the circuit caused by the evolution of gasfrom the coal or by increase of temperature accumulates in holder [8,whence it is withdrawn as desired through pipe l9 and valve 20. Howevera portion or all of this excess gas may be consumed during this stage byburning the same in the superheater 21 and not pass into gas holder l8.

During the third stage, blower '22 is stopped, damper 26 is opened anddamper 40 is partially or entirely closed, thus causing a portion or allof the gas to pass through the superheater 21 to increase itstemperature in conduit 2' to the desired point which will be about 800C. During this stage the coal will be highly heated and gas will beevolved from it. Any excess of gas in the circuit caused by evolution ofgas from the coal or by increase of temperature will pass through cooler11 and accumulate in holder I8, whence it is withdrawn as desiredthrough pipe l9 and valve 20. However-a portion or all of this excessmay be consumed during this stage by burning the same in the superheater21, and not pass into holder 18. During this stage the temperature ofthe gas reaching the blower 15 may be regulated by regulating the damperl 2 to cause some of the gas to pass through theboiler I4 and becomecooled, so that the temperature of the gas reaching blower I5 is nothigh enough to cause damage to the blower. This stage is completed whenthe temperature of the gas leaving retorts I is nearly the same as thatof the gas entering retorts I.

In order to prevent the carbonized residue from igniting when removedfrom the retorts, and also to utilize a part of its heat for heating upfresh material, the third stage is followed by a cooling stage. Valves42' and 43' and 6 are closed and valves 4, 43 and 42 are opened, thusallowing gas from gas holder I8 to flow through pipe 25 into retorts land displace the air therein. Then valve 4 is closed, valves 6, 42' and43opened, blower I5 is started, and the gas is caused to circulatethrough retorts I and retorts I asalready described previously for thefirst stage.

Many modifications and changes may be made without departing from thespirit and scope of our invention as defined in the claims and thedesire therefore is that the foregoing description and drawings beregarded in the illustrative sense rather than in a limiting sense.

We claim:

1. The process of distilling coal by the successive passage of aplurality of currents of heated gas at different times that issubstantially nonreactive'with the coal at the existing temperatures,the temperature of each current being independently controlled.

2. The process of distilling coal by the successive passage of aplurality of independent currents of heated gas at different times thatis substantially non-reactive with the coal at'the existingtemperatures, the temperature of each current being independentlycontrolled.

the coal, that is condensible at ordinary temperature, to thetemperature of substantial elimina tion thereof, and the rate oftemperature rise during at least a portion of the period of action ofsaid currents being lower than that which would cause substantialswelling of the coal used.

4. The process of distilling coal by the passage of a plurality ofcurrents of heated gas that is substantially non-reactive with the coalat the existing temperatures, the temperature of the coal due to one ofsaid currents extending to a point between 275 and 350 C., and thetemperature of the coal due to another of said currents extendingtherefrom to a point below 550 C.,

and the rise in temperature during a period between said first-mentionedpoint and 550 C. being at a rate less than one fourth of a degree C. perminute.

5. The process of distilling coal by the passage of a plurality ofcurrents of heated gas that is substantially non-reactive with the coalat'the existing temperatures, the temperature of the coal -due to one ofsaid currents extending to a peratures said gas being substantiallynon-reactive with the coal at the different temperatures, thetemperature of the current while the organic vapors from the coal arebeing removed, which condense on cooling at ordinary temperatures, beingsuch that the temperature of the coal is increased more slowly than thesubstantial swelling rate o'f the coal used.

7. In a process of distilling coal while it is stationary by the actionof a plurality of currents of heated gas at different times that issubstantially non-reactive with the coal at the existing temperatures,blending with the gas a portion of more highly heated gas, the gas to behighly heated having been substantially freed from the vapors of organiccompounds condensible at ordinary temperature.

8. In a process of distilling coal while it is staof heated gas atdifferent times that is substantially non-reactive with the coal at theexisting temperatures the addition to that current from whichcondensible organic vapor is being removed of the requisite volume, ofgas, not substantially containing condensible organic vapors, tomaintain the pressure in the current.

9. In a process of distilling coal while it is stationary by the actionof a plurality of currents of 'gas at difierent times that issubstantially non-reactive with the coal at the existing temperatures,the compensation of volume of a gas current by returning thereto gasfrom which condensed vapors have been removed, the excess gas whichrepresents that evolved from the coal being availed of in asubstantially uncontaminated condition for purposes outside thecirculating system.

10. In a process of distilling coal while it is stationary by the actionof a plurality of currents of gas that is substantially non-reactivewith the coal at the existing temperatures, dividing the coal into aplurality of charges and timing the action of the respectivecurrentsupon said charges so that a fully carbonized hot charge iscooling at the same time that a raw charge is being heated, andtransferring the heat from the carbonized charge to the raw charge bycirculation of the gas through both charges.

11. In a process of distilling coal by the action of a plurality ofcurrents of non-oxidizing gas that is substantially non-reactive withthe coal at the existing temperatures, passing the gas from a current toa gas holder through a cooler when there is an increase of volume in thecurrent and from the gas holder when there is a decrease of volume inthe current.

12. In a process of distilling coal by the action of a. plurality ofcurrents of non-oxidizing gas at different times that is substantiallynon-reactive with the coal at the existing temperatures, a cooling ofthe fully carbonized hot coal by the circulation therethrough of coldergas in a closed current, the gas leaving the hot charge being deprivedof part of its heat before being returned to the charge.

13. The process of distilling coal while it is stationary by thetreatment ir a plurality of stages with heated gas that is substantiallynon-reactive with the coal-at the existing temperatures, one of saidstages extending from the temperature of the substantial appearance ofvapor condensible at ordinary temperature to the temperature ofsubstantial elimination thereof, and the rate of temperature rise of thecoal during at least a substantial portion of said stage being lowerthan that which would cause substantial swelling of the coal used.

14. The process of distilling coal by currents of heated gas that issubstantially non-reactive with the coal at the existing temperatures,which consists in raising its temperature by currents of heated gasesabove 600 C. where the desired density and reactivity of the carbonizedproduct are obtained, while limiting the rate of heat increment, duringat least part of the stage of vaporizing which produces vapors that arecondensible on cooling to ordinary temperature below that which wouldcause substantial swelling of the coal used.

15 The process of distilling coal in three stages by currents of heatedgases, in the first of which the increment of temperature per unit oftime is comparatively great until that temperature is reached abovewhich organic vapors condensible at ordinary temperature would besubstantially evolved, in the second of which stages the vaporscondenslble on cooling to ordinary temperature are substantiallyeliminated and which stage includes a period of comparatively small heatincrement per unit of time, and in the third of which stages the heatincrement is more rapid than in the second stage.

16. The process of transforming bituminous coal into a plurality ofproducts such as solid fuel, tar and coal gas which comprises formingthe coal into briquets, then rapidly raising the temperature of the sameby currents of heated gases to the point above which vapors of organiccompounds condensible at ordinary temperatures would be evolved,subsequently distilling tar and hydrocarbons condensible at ordinarytemperatures while raising the temperature at a rate not exceeding thatwhich would cause the coal to swell substantially, and thereafterrapidly raising the temperature to about 600 C. to 900 C GEORGE A.BERRY. ALLING P. BEARDSLEY.

